1. Field of the Invention
The present invention relates to an electro-optical light controlling panel. More particularly, it relates a light controlling panel utilizing an electrochromic material and having infra-red reflecting characteristic.
2. Description of the Prior Arts
A glass panel utilizing electrochromic phenomenon will be used as a light controlling glass panel. The light controlling glass panel can automatically or manually control the light transmission through the panel in response to the intensity of the incident light as rapidly as desired, and will be used as a window glass for a building, a car or an airplane or a cover glass panel for a picture surface of a television.
Such light controlling glass panel substantially comprises a glass plate, a transparent electroconductive film as an electrode formed on the glass plate, a tungsten oxide layer as an electrochromic material formed on the film, an electrolyte layer containing a proton or an alkali metal ion which contacts with the tungsten oxide layer and an electroconductive film as a counter-electrode which contacts with the electrolyte layer in a basical structure.
When a negative potential is applied to the electrochromic material of the light controlling glass panel, cations and electrons corresponding to the cations are injected whereby the cations and electrons are mutually affected to the electrochromic material to result in light absorptions in the visible region. Such phenomenon is considered to be caused by the fact that the color center is formed by the following reaction to color the film blue when negative potential is applied to a tungsten oxide film.
WO.sub.3 (colorless)+XM.sup.+ +Xe.sup.- .fwdarw.M.sub.x WO.sub.3 (blue color) wherein M.sup.+ represents a proton or a cation such as an alkali metal ion.